Roller strip filter for purifying air or gases

ABSTRACT

A roller-strip filter for air or gas purification, which can be easily disassembled, consists of two units separable from each other. The first unit comprises a mounting framework, seals for the filter strip and support grids for backing the filter strip , guide rollers for the filter strip; the second unit comprises feed and wind-up rollers for moving the filter strip and a drive unit for rotating the wind-up roller, whereby the more delicate components can be mounted in the filter framework after fitting the framework to a wall portion or the like.

United States Patent [15] 3,695,008 Neu mann 1 Oct. 3, 1972 [54] ROLLERSTRIP FILTER FOR 3,003,582 10/1961 Palmore ..55/354 PURIFYING AIR ORGASES 3,280,539 10/1966 Parrott ..55/354 3,359,709 12/1967 Revell..55/354 [72] Gum"! 'm Balm Germany 3,552,101 1/1971 Papp ..55/354 [73]A'ssignee: Delbag-Luftfilter Gesellschaft mit 3,559,380 2/1971 Neumann..55/354 beschrankter Haftung, Berlin, Germ ny Primary Examiner-BemardNozick 221 Filed: Jan. 15, 1970 [21] A pl. No.: 2,995 57 AB TR Aroller-strip filter for air or gas purification, which ForelgnAppllcatlon y Data can be easily disassembled, consists of two units Jam21, 1969 Gem'lany 02 635 separable from each other. The first unitcomprises a Jan. 21, 1969 Germany ..G 69 02 636 mounting framework,Seals for the filler Strip and P- Jan. 21, 1969 Germany ..G 69 02 637 Pgrids for backing the filter strip 1 guide rollers for the filter strip;the second unit comprises feed and 52 us. c1. ..55/354, 55/484, 55/501wind-up rollers for moving the filter strip and a drive 51 Int. Cl...B01d 25/24 unit for rotating the p roller, whereby the more 58 Field61 Search ..55/351-354, 484, delicate components can be mounted n h filr 55/501 framework after fitting the framework to a wall portion or thelike. [56] References Cited I UNITED STATES PATENTS l/l922 Smith..55/354 23 Claims, 17 Drawing Figures PATENTEDncI 3 m2 SHEET 1 BF 9GERHARD NEUHAIN lnv ento r:

Rm {Kar I I ATTORNEY PATENTEBBBTB I912 3.695.008

' sum 3 or 9 Fig.4

Inventor:

Bx R m PATENTEDnma 9 3.695.008

sum 5 or 9 6211mm nzmmm lnvenfa r:

BY 6 {B 6 w PATENTEDHBT 3 I972 SHEET 7 [IF 9 Fig.10

all

GLRILiR D N LUrlnlJ l3 PmEmEnucrs m2 f 3,695,008

SHEUBUFQ I Gi-LRHARJ ram-Lam;

Inventor:

J. with?! PATENTEDUBT 3 I972 SHEET 9 BF 9 G ARBAR D N Lilith N ln-ven tor Q as M g. ,0

ROLLER STRIP FILTER FOR PURIFYING AIR OR GASES My present inventionrelates to a roller-strip filter.

Such filters are used for purifying atmospheric air, for example inair-conditioning systems, and are as a rule arranged in a wall opening.They have an upper or feed roller and a lower or wind-up roller drivenintermittently by a drive mechanism. The wind-up roller draws a filterstrip over a filter surface lying between the two rollers. The filterstrip is held on both sides by support grids between the two rollers toprevent the strip from bulging out of its plane of motion. Conventionalroller-strip filters have casings in which all the functional componentsof the filter are preassembled at the factory. The completelyassembled'roller-strip filter is transported to the place ofinstallation from the factory in order to be fitted in the wall opening.With these roller-strip filters it is necessary to use a specialmounting framework since, as they lack attachment flanges, they cannotbe fitted directly into a wall opening. Besides, as a result of the workon the wall and plaster, there is a danger of the somewhat sensitivefunctional components becoming dirty and being damaged. Apart from thesedisadvantages the production and transport costs for these knownroller-strip filters in the assembled state are considerable;construction of the casing and the installation of the functionalcomponents entail considerable mounting time and costs. Knownrollerstrip filters with mounting frameworks are not universallyapplicable, e.g., for devices lying on end. If it is required to inserta new feed roller with filter strip in the roller-strip filter, the newroller has to be fitted in the holder upon removal of the empty feedroller. The filter strip is then threaded over the upper deflectingroller between the support grids until it can be fixed to the lowerroller. Inserting the full feed roller into its holder and threading thefilter strip between the support grids is difficult in the case ofconventional rollerstrip filters, particularly because the full feedroller is in its operational position and therefore there is very littleroom for threading the filter strip.

The wind-up roller is driven intermittently by a drive system, held inthe framework forming the housing, through the intermediary of a rollersprocket acting on a chain wheel of the wind-up roller; it draws offfrom the upper roller the necessary length of filter strip when the partof the filter strip between the support grids has all been used up byimpurities from the air. The need for rapidly replacing the drivenwind-up roller in such filters involves a not inconsiderable cost withregard to the both drive itself and the required rapidly releasablemounting for the wind-up roller. Exchanging the windup roller itself inthat case is difficult and costly and takes a relatively long time whichis a special disadvantage since the strip filter does not operate duringthe replacement. In various known constructions either each individualroller-strip filter is provided with its own drive, which in the case oflarge installations with several roller-strip filters in series causesan unnecessary expense, or two roller-strip filters can be driven by thedrive system by means of intermediate coupling components. However, inmost cases these coupling components are too costly and do not allow thedrive arrangement to be modified.

Objects of the invention are to avoid these disadvantages and to producea roller-strip filter which is inexpensive in construction, isuniversally applicable and can be fitted into a wall opening in variousassembly stages along with its mounting framework without danger ofdamaging or dirtying the important functional components of the filter,which enables a simple mounting for the strip rollers and simplifies thework of threading the filter strip, which is distinguished by a simpleand cheap construction of the feed roller and its mounting, whichfacilitates rapid exchange with reliable operation, and which allows twoadjacent or interconnected roller-strip filters to be actuatedsimultaneously by a common drive system fitted to one filter.

The roller-strip filter according to my invention includes a first unitand asecond unit, the first unit comprising a mounting framework, asealing profile mountable thereon at either side of the filter strip,support grids for either side of the filter strip, and deflectingrollers for the filter strip; the second unit comprises a support for awind-up roller and a feed roller as well as a drive unit for driving thewind-up roller.

By dividing the conventional casing in accordance with the inventioninto a mounting framework and a roller support with the functionalcomponents fixed to it, the mounting costs, the production costs and theassembly costs and time may be considerably reduced. The mountingframework may be fitted directly into the wall opening. When thesubsequent plastering has been completed, the sealing profile, thesupport grids and the deflecting rollers for the filter strip can bearranged in the mounting framework. The mounting framework could also beinstalled together with its associated functional components in the wallopening. The functional components carried on the support may bepreassembled at the factory ready for operation so that little work isinvolved in assembling the mounting framework and the support at theplace of use.

The mounting framework may be made up of an angled profile in the formof a double channel with parallel free edges facing in oppositedirections, the profile forming two longitudinal rails with the samecross section and an upper and a lower transverse rail connectedthereto. The inside channel portion of the rails may have a central webwhich is wider than that of the outside channel portion and serves as abackstop for the longitudinal edges of the filter strip. Thanks to theuse of this special angled profile the production costs for the simplemounting framework are very low. The mounting framework may be fixed ina wall opening by the central web of the outer channel portion of therail at the ends of the longitudinal rails; the leg of the outer channelportion has bridging tongues for engaging the support. In addition theblacking grid on the air exhaust side may be held in the transverseupper and lower rails of the mounting framework. The two lateral sealingprofiles for the filter strip-may each consist of an angle iron whichcan be fixed with one leg by way of slots to the common leg of the twochannel portions of the longitudinal rails of the mounting framework soas to be adjustable in a direction perpendicular to the filter strip.The free leg of the sealing profile may terminate in a bend lying withits front edge on the filter strip and may have its central regionbraced by a spring against the central web of the inside channel portionof the mounting framework, the spring surrounding a bolt for adjustingthe sealing profile to the thickness of the filter strip. By virtue ofthe arrangement and design of the sealing profile in accordance with theinvention the roller strip filter can be adapted very easily to filterstrips of varying thickness, reliable and dependable sealing of theadvancing filter strip against air leakage being ensured in every case.In addition the sealing profiles may form the longitudinal sides of theair-intake side of the support grid and at their two ends carry thedeflecting rollers for the filter strip, the rods of the air-intake sideof the support grid being held in transverse channels fixed to the upperside of the free leg of the sealing profile. The special design of thesealing profile as side parts of the support grid carrying thedeflecting rollers ensures that, upon adjustment to a given filter-stripthickness, simultaneously and automatically the support grid and theupper and lower deflecting rollers are adjusted to the same extent.

The support may consist of two angle-iron members to be fixed to thetongues of the outer channel portions of the longitudinal rails of themounting framework, which may be interconnected by cross rods engagingthe ends of the central webs. Using angle irons for the support lowersthe cost and simplifies handling and mounting. The central webs of themembers may sup port the drive system, the feed and wind-up rollers anda cover plate. The free legs of the outer channel portions of thelongitudinal rails of the mounting framework may have elongated screwholes for joining together two adjacent mounting frameworks.

Furthermore, in the upper region of the rear side of the housing orframework construction there may be fixed a pair of retaining lugsprojecting from the longitudinal sides perpendicularly to the axis ofthe feed roller and having in their upper edges a vertical orapproximately vertical recess acting as a bearing for the shaft of thefeed roller; their front edges may be provided below that recess with asecond recess extending obliquely upwardly to serve as a temporary restfor the full feed roller while the filter strip is being insertedbetween the support grids. Thus, the filter strip can be easily threadedinto the support grids from the full roller. To do this the full roll isfirst placed in the obliquely sloping recesses in the front edges of thelugs. The roller is thus below its operational position so that there issufficient space for handling the filter strip during the process ofthreading it in. Once the filter strip has been inserted and takenup bythe lower wind-on roller, the full feed roller is simply moved out ofthe obliquely sloping recesses into the recesses in the upper edges ofthe lugs; the fed roller is then in the correct operational position.When exchanging an empty feed roller for a full one, the empty onemerely has to be removedfrom the recesses in the upper edges of thelugs; the full feed roller may now be placed in the oblique recesses ofthe lugs, the filter strip may then be fed in and the full feed rolleris thereupon lodged in the vertical recesses for operation. These lugsmay each have a resilient latch which may be positioned to pivot on apin when the roller-strip filter is to lie face down. In this case thefeed roller cannot fall out of the recess in the lug.

The feed roller on the dirty-air side of the retaining lugs may have thelower part of their outer surfaces provided with projecting pins servingas rocker bearings for a domed cover. With the lugs and below theiroblique recesses there may be pins projecting at right angles foranchoringa tension spring whose other end is attached to the domedcover. In the case of roller-strip filters in which the wind-up and feedrollers are located on the dirty-air side, the upper or feed rollershould be protected from the effects of the dusty air by theaforementioned dome cover. The arrangement just described makes it easyto handle the domed cover during the exchange process; in operation thedomed cover is held in the closed position by the force of the springswhereas when the cover is tipped back still tensioned springs are in adead-center portion.

If the feed roller lies on the clean-air side downstream of the airflow, the pins acting as rocker bearing and the pins engaging thetension springs may be arranged on lugs projecting beneath the bearingsfor the feed roller.

The sprocket-wheel of the chain drive may be held with its axle in abearing positioned on the outside of one of the longitudinal members ofthe framework and may be provided at its exposed face with adiametrically extending coupling bar of U-shaped or preferablyrectangular cross section; the wind-up roller can carry at one end ofits shaft an entrainment disc having on its free surface acomplementan'ly shaped coupling element engageable with the bar, theother end of its shaft being releasably held in a bearing on theopposite longitudinal member of the framework.

The cast or plastic bearing for the roller shaft may comprise a lowerU-shaped upwardly open part fixed to the longitudinal member for takingthe roller shaft and a U-shaped downwardly open upper part offset byfrom the lower part, movable on the longitudinal member in a verticaldirection and fitting in its closed bearing position over the lowerpart; the rear arm of this upper part acts as a stop for the free end ofthe roller shaft, its front arm having a downwardly open recess of alength equalling the diameter of the roller shaft.

The upper slidable bearing part may have fixed to its central web anupstanding, vertically displaceable mounting loop guided by a fasteningscrew.

The free end of the sprocket wheel shaft may be in the form of afour-cornered stud projecting from the bearing, which can be coupled bya four-cornered sleeve with the four-cornered shaft of a drive platehaving a U-shaped projection engageable with the wind-up roller of anadjoining strip filter.

In the accompanying drawing:

FIG. 1 shows a schematic perspective view of a roller-strip filterembodying my invention;

FIG. 2 shows a perspective exploded view of the mounting framework andof the support of my improved filter; 7

FIG. 3 shows a perspective view of the support grid carrying thedeflecting rollers;

FIG. 4 shows a cross section through the mounting framework with thesupport grids and sealing elements;

FIG. 5 shows a cross-sectional elevation of the mounting framework and adiagrammatic side view of the support;

FIG. 6 shows a perspective view of a lug fixed to the framework as aholder for the upper or feed roller;

FIG. 6a shows a perspective view of the lug with locking bar;

FIG. 7 shows a diagrammatic side view of the rollerstrip filter withouthood;

FIG. 8 shows the upper part of FIG. 7 together with a domed cover orhood for the upper roller in open positron;

FIG. 8a is a view similar to FIG. 8 with the hood closed;

FIG. 9 shows the lower part of FIG. 8 together with a domed cover orhood for the lower roller in open positron;

FIG. 9a is a view similar to FIG. 9' with the hood closed;

FIG. 10 shows a diagrammatic face view of the assembly of FIG. 1;

FIG. 11 shows a magnified perspective view bearing for the shaft of thewind-up roller;

FIG. 12 shows a perspective view of the driving sprocket wheel of thewind-up roller;

FIG. 13 shows a partial view of two wind-up rollers coupled together;and

FIG. 14 shows a perspective exploded view of the elements of FIG. 13drawn to a larger scale.

FIG. 1 shows the mounting framework 1, the carrier support 2, the loweror wind-up roller 3, the upper or feed roller 4, the domed cover or hood5, the drive system 6 for the wind-up roller and one support grid 7 ofmy improved filter. As can be seenfrom FIGS. 2, 4 and 5, the mountingframework 1 comprises longitudinal rails 8 and transverse rails 9. Therails 8 and 9 have a generally S-shaped channel profile, as shown moreclearly in FIG. 4. The outside channel section or U of the profiled railhas a free leg 10, a central web 11 and a leg 12 attached to a centralweb 13 of the inside channel section or U which ends in a free leg 14.The outside channel section of the longitudinal rails 8 is closed aboveand below by a bridgeing tongue or plate 15 which serves for attachingthe support 2 to th frame 1. v

The support 2 comprises two bail-shaped upright bf the I members 16 ofangle iron whose angularly bent extremities 17 are attached by means oftransverse lugs 18 thereof to the bridge plates 15 of the longitudinalrails 8 of the mounting framework 1. The two uprights 16 of the supportframework 2, joined together by cross bars 19, carry on their centralwebs the drive system 6, the roller 4 and the domed cover 5 not depictedin FIG. 2.

As FIGS. 2 and 4 show, the legs 10 of the outside channel sections ofthe longitudinal rails 8 of the mounting framework 1 have screw holes 21through which, as can be seen in particular from FIG. 4, the legs 10 oftwo adjacent mounting frameworks can be joined together be screws 22 toform one unit. As FIG. 4 shows, the central web 11 of the outsidechannel section of the rails 8, 9 lies against a wall to which themounting framework 1 is anchored by clamps 23. Fitted to the assembledmounting framework 1 and support 2 is an upper cover plate whichprotects the roller-strip filter from foreign bodies (e.g. dust) fallingAs FIG. 4 further shows, the sealing profile 24 consists of an angleiron, one arm 25 of which lies against the common leg 12 of theS-profile 10-14 while its other arm 26 forms a pressure bar whichextends over the web 13 of the inside channel section of thelongitudinal rail 8. At its free edge the arm 26 has a bend 27 whichbears upon the front face of the filter strip 28 and holds it tightagainst the surface of web 13. The arm 25 has a slot 36 traversed by ascrew 29 whereby the sealing profile 24 is adjustably mounted on themember 8. Fixed to the central web 13 is a screw bolt 30 which passesthrough the arm 26 of the sealing profile 24 with interposition of aspring 31. The effective depth sealing profile is adjusted by operatinga wing nut 32 engaging screw bolt 30.

The vertical guide rods of grid 7 are received, as FIG. 4 shows, in thecross rails 9 of the mounting framework. The other support grid 34 (FIG.3), carrying the deflecting rollers 33 for the filter strip 28,comprises vertical guide rods 37 held by horizontal channel rails 38 onthe vertical profiles 24 which simultaneously form the carriers 25 forthe whole functional unit. In the ends of the flanges 25 of profiles 24are mounted the deflecting rollers 33.

In assembling the roller-strip filter at the place of use, the mountingframework 1, with its rectangular structure 8, 9 spanned by rods 7 andthe support grid 34 carried on the sealing profiles 24 along with thedeflecting rollers 33 is fixed in front of or in the nonillustrated wallopening which is traversed by the airstreamto be filtered. The support 2with the drive system 6, the rollers 3, 4 and the domed cover 5 is thenfixed thereto by the brackets 15 of the longitudinal rails 9 of themounting framework 1. After threading the filter strip 28 between thesupport grids 7 and 37 and winding it onto the wind-up roller 3, theroller-strip filter is ready for operation.

As FIG. 6 shows for one of the two upright members 16, each of thesemembers carries, a projecting lug or plate 39. In its upper edge theplate has a recess or notch 40 which ends in a semi-circle and acts as arest or bearing for the shaft of the feed roller 4. In the front edge ofthe plate 39 underneath the recess 40 there is a recess or slot 41sloping obliquely upwards to receive the pay-off roll 4 while the filterstrip is being threaded between the support grids 7 and 34. Projectinghorizontally from the outside of the plate 39 is a lower pin 42 whichserves as rocker bearing for the domed cover or hood 5. On the inside ofthe plate 39, below the recess 41 and above the pin 42, there is aprojecting pin 43 to which is fixed a tension spring 44 attached by itsother end to the domed cover 5, as shown in FIG. 8. Here the feed rolleris on the dirty-air or upstream side of the roller-strip filter and isprotected from the effects of the dusty air by the closed hood 5. Incases where the filter lies flat a resilient, generally L-shaped latch46 (FIG.

6a) is pivoted on the pin 42 to close off the recesses 40 and 41 whenthe latch is swung up.

When the rollers 3, 4 are arranged on the clean-air or downstream side(FIG. 9), the lower or wind-up roller 3 has to be protected from thedusty air. In this case the domed cover 5 engages lugs 45 each fixed toa respective bar 16 beneath the bearing for the wind-up roller 3 andcarrying the pivot pin 42 as well as the anchor pin 43. In this way theroller-strip filter in accordance with the invention can be used asdesired, with the rollers either on the upstream side or on thedownstream, with one and the same domed cover.

As FIG. 11 shows, the right-hand longitudinal member 16 seen in FIGS. 1and 10 carries a lower bearing part 46 and an upper bearing part 47. Thelower part 46 has a strip 48 bent into a U open at the top into which isinserted the end 49 of the shaft of the wind-up roller 3. The upper part47 is likewise U-shaped but is turned through 90 with respect to thelower part 46. Fixed to the central web 50 of the upper bearing part 47is a vertical loop 51; positioned on the upright 16 are a fixing screw52 and an adjusting screw 53 which allow the upper bearing part to beadjusted in a vertical direction. FIG. 11 depicts the bearing parts 46,47 in the open position. When a new wind-up roller 3 is inserted intothe lower bearing part 46, the upper bearing part 47 is slid downwardswith its rear leg 54 acting as an end stop for the end 49 of the rollershaft while a downwardly open recess 56 in the front leg 55 fits overthe end 49 whereby the wind-up roller 3 is held securely in the bearingparts 46, 47 without being able to slip sideways or longitudinally in anon-edge position. Upon a lowering of bearing half 47 into itsshaft-retaining position, bearing half 48 is straddled by the recessedleg 55 and the solid leg 54 which are spaced apart in the axialdirection of the roller shaft.

FIGS. 12 to 14 show the design of the drive system and the other side ofthe wind-up roller 3. FIG. 12 shows that the shaft of the sprocket wheel59 is held in a bearing 57 on the upright 16. The exposed front surfaceof the sprocket wheel has a diagonal rib 60. On the adjacent end of thewind-up roller 3 there is provided an entrainment disc 61 which has abox-shaped, forwardly open projection 62 with a closed periphery whichengages the rib 60 so that the wind-up roller 3 is positively entrainedby the drive sprocket 59. Since the rear arm 54 of the upper bearingpart 47 prevents the wind-up roller from shifting axially, the box-likeprojection 62 of the end disc 61 cannot under any circumthe drive wheel59 during operation, i.e., when the bearing parts 46, 47 are closed.When it is necessary to change the wind-up roller all that has to bedone is to raise the upper bearing part 47 from the closed position intothe position shown in FIG. 11. Then the wind-up roller 3 can first bedisplaced axially and withdrawn from the projection 60 and the bereleased from the lower bearing part 48. When inserting a new emptywind-up roller, the box-like projection 62 of the end disc 61 is fittedover the projection 60 of the drive wheel 59 and the shaft end 49 isinserted into the lower bearing part 46, after which whereupon the upperbearing part 47 is pushed down from the open position in FIG. 11 intothe closed position. In this way the windup roller 3 is securely held bythe bearing 46, 47 against axial and lateral displacement.

As FIG. 12 shows, the stub shaft of the sprocket wheel 59 has afour-cornered extremity 63 extending out of the bearing 57 almost to theoutside edge of the longitudinal member 16. When two rollerstrip filtersare mounted side by side, a stub shaft 66 of a coupling disc 65 issimply inserted into the bearing 57 in the adjoining upright 16 of theadjacent roller-strip filter, the shaft of this disc likewise having afour-cornered mating extremity. The coupling disc 65 has a bar-shapeddiametrical rib 60 similar to that of the wheel 59. The twofour-cornered shaft ends 63 have fitted over them a four-cornered sleeve64 so that the disc 65 is coupled with the wheel 59.

The construction in accordance with the invention allows rapidinterchange of the wind-up roller as well as convenient interconnectionof the wind-up rollers of two adjacent roller-strip filters so that theycan be operated by one and the same drive system.

I claim:

1. A roller-strip filter comprising:

a mounting framework fitting into a wall opening, said frameworkincluding a rectangular structure with a pair of vertical member and apair of transverse horizontal members surrounding an air passage, saidvertical members defining a pair of coplanar sealing surfaces onopposite sides of said air passage;

strip-guiding means on said structure including a pair of grids spanningsaid air passage with sufficient separation to form a path therebetweenfor a vertically movable filter. strip advancing across said openingalong said sealing surfaces;

a pair of uprights provided with fastening means removably attachingsame to said vertical members outside said sealing surfaces;

a feed roller supplying said filter strip and having a first horizontalshaft joumaled on said uprights adjacent one of said horizontal members;

a wind-up roller taking up said filter strip and having a secondhorizontal shaft joumaled on said uprights adjacent the other of saidhorizontal members;

drive means for said second shaft on one of said uprights; and

a pair of pressure elements carried on said framework for holding thelateral edges of said filter strip tight against said sealing surfaces.

2. A filter as defined in claim 1 wherein said pressure bars are partsof a pair of angled profiles having other parts adjustably mounted onsaid vertical members, one of said grids comprising a set of verticalrods mounted on said horizontal members, the other of said gridscomprising a set of rods carried on cross bars interconnecting saidprofiles.

3. A filter as defined in claim 2 wherein said vertical members areprofiled bars of generally S-shaped profile with intermediate legssecured to said other parts and with webs spacedly overlain by saidpressure bars.

4. A. filter as defined in claim 3 wherein said webs are provided withspring-loaded clamping bolts engaging said pressure bars .for selectiveadjustment of the spacing between said webs and said pressure bars.

5. A filter as defined in claim 3 wherein said profiled bars formchannels open toward said uprights and pro vided with bridgingformations engaging said uprights at the top and the bottom thereof.

6. A filter as defined in claim 5 wherein said uprights are bail-shapedmembers with bent-over top and bottom extremities terminating intransverse lugs secured to said bridging formations.

7. A filter as defined in claim 1 wherein said uprights are bail-shapedmembers with bent-over top and bottom extremities fastened to saidvertical members, further comprising cross braces interconnecting saiduprights at corners formed by said bent-over extremities.

8. A filter as defined in claim 7 wherein said uprights are providednear said top extremities with lugs projecting away from said frameworkand forming rests for the ends of said first shaft.

9. A filter as defined in claim 8 wherein said lugs have upper edgesprovided with vertical notches constituting said rests.

10. A filter as defined in claim 8 wherein said lugs have vertical edgesprovided with downwardly slanting recesses constituting alternate restsadapted to receive the ends of said first shaft during insertion of afilter strip from said pay-off roller between said grids.

11. A filter as defined in claim 10 wherein said lugs are provided withgenerally L-shaped latches swingable into positions obstructing saidnotches and said recesses.

12. A filter as defined in claim 8, further comprising a hood for saidpay-off roller pivotally mounted on said lugs.

13. A filter as defined in claim 12, further comprising tension springsanchored to said lugs and to said hood for urging same into a closedposition.

14. A filter as defined in claim 7 wherein the other of said uprights isprovided near its bottom extremity with a fixed, upwardly open bearinghalf for an end of said second shaft and with a complementary,vertically movable bearing half.

15. A filter as defined in claim 14, further comprising fastening meansengageable with said complementary bearing half for fixing same in ashaft-retaining position.

16. A filter as defined in claim wherein said complementary bearing halfforms an end stop for said second shaft.

17. A filter as defined in claim 16 wherein said complementary bearinghalf has two depending legs spaced apart in the axial direction of saidsecond shaft, said legs bracketing said upwardly open bearing half insaid shaft-retaining position, one of said legs having a bottom recessgiving clearance to said second shaft, the other of said legs beingsolid and constituting said end stop.

18. A filter as defined in claim 14 wherein said drive means comprises amotor-driven wheel coaxial with said second shaft, the latter beingprovided with a disk adjacent said wheel, said wheel and said diskhaving confronting surfaces provided with mating formations forpositively coupling said second shaft to said wheel upon the remote endthereof engaging said end stop.

19. A filter as defined in claim 18 wherein said mating formationsinclude a diametrical rib on one of said confronting surfaces and acomplementary box-shaped diametrical projection on the other of saidconfronting surfaces.

20. A filter as defined in claim 18 wherein said wheel is provided withsprocket teeth engageable by a drive chain.

21. A filter as defined in claim 18, wherein the upright carrying saidwheel is juxtaposed with a similar upright on an adjoining secondframework, further comprising coupling means on said similar uprightengageable with said wheel for entraining another windup roller on saidsecond framework.

22. A filter as defined in claim 21 wherein said cou lin means com risesa second disk ha in t b sha ali gned with a tub shaft of said wheel s i2:31)

shafts being releasably interconnected for joint rotation.

23. A filter as defined in claim 22 wherein said stub shafts areprovided with polygonal ends confronting each other and with acomplementary connecting sleeve engaging said polygonal ends.

1. A roller-strip filter comprising: a mounting framework fitting into awall opening, said framework including a rectangular structure with apair of vertical member and a pair of transverse horizontal memberssurrounding an air passage, said vertical members defining a pair ofcoplanar sealing surfaces on opposite sides of said air passage;strip-guiding means on said structure including a pair of grids spanningsaid air passage with sufficient separation to form a path therebetweenfor a vertically movable filter strip advancing across said openingalong said sealing surfaces; a pair of uprights provided with fasteningmeans removably attaching same to said vertical members outside saidsealing surfaces; a feed roller supplying said filter strip and having afirst horizontal shaft journaled on said uprights adjacent one of saidhorizontal members; a wind-up roller taking up said filter strip andhaving a second horizontal shaft journaled on said uprights adjacent theother of said horizontal members; drive means for said second shaft onone of said uprights; and a pair of pressure elements carried on saidframework for holding the lateral edges of said filter strip tightagainst said sealing surfaces.
 2. A filter as defined in claim 1 whereinsaid pressure bars are parts of a pair of angled profiles having otherparts adjustably mounted on said vertical members, one of said gridscomprising a set of vertical rods mounted on said horizontal members,the other of said grids comprising a set of rods carried on cross barsinterconnecting said profiles.
 3. A filter as defined in claim 2 whereinsaid vertical members are profiled bars of generally S-shaped profilewith intermediate legs secured to said other parts and with websspacedly overlain by said pressure bars.
 4. A filter as defined in claim3 wherein said webs are provided with spring-loaded clamping boltsengaging said pressure bars for selective adjustment of the spacingbetween said webs and said pressure bars.
 5. A filter as defined inclaim 3 wherein said profiled bars form channels open toward saiduprights and provided with bridging formations engaging said uprights atthe top and the bottom thereof.
 6. A filter as defined in claim 5wherein said uprights are bail-shaped members with bent-over top andbottom extremities terminating in transverse lugs secured to saidbridging formations.
 7. A filter as defined in claim 1 wherein saiduprights are bail-shaped members with bent-over top and bottomextremities fastened to said vertical members, further comPrising crossbraces interconnecting said uprights at corners formed by said bent-overextremities.
 8. A filter as defined in claim 7 wherein said uprights areprovided near said top extremities with lugs projecting away from saidframework and forming rests for the ends of said first shaft.
 9. Afilter as defined in claim 8 wherein said lugs have upper edges providedwith vertical notches constituting said rests.
 10. A filter as definedin claim 8 wherein said lugs have vertical edges provided withdownwardly slanting recesses constituting alternate rests adapted toreceive the ends of said first shaft during insertion of a filter stripfrom said pay-off roller between said grids.
 11. A filter as defined inclaim 10 wherein said lugs are provided with generally L-shaped latchesswingable into positions obstructing said notches and said recesses. 12.A filter as defined in claim 8, further comprising a hood for saidpay-off roller pivotally mounted on said lugs.
 13. A filter as definedin claim 12, further comprising tension springs anchored to said lugsand to said hood for urging same into a closed position.
 14. A filter asdefined in claim 7 wherein the other of said uprights is provided nearits bottom extremity with a fixed, upwardly open bearing half for an endof said second shaft and with a complementary, vertically movablebearing half.
 15. A filter as defined in claim 14, further comprisingfastening means engageable with said complementary bearing half forfixing same in a shaft-retaining position.
 16. A filter as defined inclaim 15 wherein said complementary bearing half forms an end stop forsaid second shaft.
 17. A filter as defined in claim 16 wherein saidcomplementary bearing half has two depending legs spaced apart in theaxial direction of said second shaft, said legs bracketing said upwardlyopen bearing half in said shaft-retaining position, one of said legshaving a bottom recess giving clearance to said second shaft, the otherof said legs being solid and constituting said end stop.
 18. A filter asdefined in claim 14 wherein said drive means comprises a motor-drivenwheel coaxial with said second shaft, the latter being provided with adisk adjacent said wheel, said wheel and said disk having confrontingsurfaces provided with mating formations for positively coupling saidsecond shaft to said wheel upon the remote end thereof engaging said endstop.
 19. A filter as defined in claim 18 wherein said mating formationsinclude a diametrical rib on one of said confronting surfaces and acomplementary box-shaped diametrical projection on the other of saidconfronting surfaces.
 20. A filter as defined in claim 18 wherein saidwheel is provided with sprocket teeth engageable by a drive chain.
 21. Afilter as defined in claim 18, wherein the upright carrying said wheelis juxtaposed with a similar upright on an adjoining second framework,further comprising coupling means on said similar upright engageablewith said wheel for entraining another wind-up roller on said secondframework.
 22. A filter as defined in claim 21 wherein said couplingmeans comprises a second disk having a stub shaft aligned with a stubshaft of said wheel, said stub shafts being releasably interconnectedfor joint rotation.
 23. A filter as defined in claim 22 wherein saidstub shafts are provided with polygonal ends confronting each other andwith a complementary connecting sleeve engaging said polygonal ends.